PayPal Holdings Inc. vaulted over American Express Co. in terms of market value this week, punctuating a rally that has pushed up the payments company’s shares by nearly 75% since the start of 2017.

The San Jose, Calif., company has enjoyed breakneck growth in both e-commerce and mobile money transfers. Its market capitalization stands at about $83 billion, nearly double the $47 billion value it had when it spun off from eBay Inc. a little over two years ago.